1. Field of the Invention
The present invention relates to temperature compensated pressure switch with thermal lag compensation, trend indication, and forecast analysis.
2. Description of Related Art
As seen in FIG. 1, the prior art determines whether there is a sufficient amount of material in a vessel by setting a pressure threshold 10. If the pressure 12 of the vessel is above pressure threshold 10, then it is deemed that the amount of material in the vessel is sufficient and if pressure 12 of the vessel is below pressure threshold 10, then it is deemed that the amount of material in the vessel is insufficient. However, as can be seen, the pressure of the vessel is correlated with the temperature of the vessel and can greatly fluctuate with temperature increase and decreases. Thus, at 70° F. the pressure data would indicate that there is sufficient amount of material in the vessel as the pressure data would be above pressure threshold 10.
However, if the temperature is increased to 200° F. it would take a significant loss of material within the vessel to reduce the pressure data below pressure threshold 10. Thus, there would be a false indication that the pressure was acceptable. Furthermore, if the temperature was decreased from 70° F. to −30° F., and the amount of material in the vessel remained constant, the pressure data would be below pressure threshold 10. Thus, there would be false indication that the pressure was unacceptable.
Furthermore, systems which utilize a pressure sensor and a temperature sensor may still be susceptible to thermal lag conditions where the ambient temperature increases or decreases rapidly. During thermal lag conditions, the temperature sensor may inaccurately indicate that the material within the vessel has a high rate of temperature change value. However, in actuality, the material within the vessel can actually have a rate of temperature change value lower than the inaccurate high rate of temperature change value.
This can be problematic since the determination of whether there is an acceptable amount of material within the vessel is dependent on whether the pressure detected by the pressure sensor is above a minimum pressure corresponding to the detected temperature data. However, with an incorrect temperature data, there is an incorrect minimum pressure data. Thus, the system can falsely indicate that there is an unacceptable amount of material within the vessel.